JP7258584B2 - Viewing angle control device and display device - Google Patents

Description

TECHNICAL FIELD Embodiments of the present invention relate to viewing angle control devices and display devices.

In recent years, display devices have been applied to various products such as notebook computers, monitors, car navigation systems, scientific calculators, small and medium-sized TVs, large-sized TVs, mobile phones, and electronic notebooks. Among these products, display devices used in electronic diaries, personal digital assistants (PDAs), mobile phones, tablet computers (PCs), notebook PCs, etc. are light, thin, short and small, and are often carried around. In addition, the display devices for ATM (automated teller machine) and ticket vending machine products are often used in public places.

In the above-described products, depending on the usage conditions, it may be troublesome if the display contents are identified by others. For example, when displaying private content on a mobile phone, PDA, or tablet PC in a public setting. In such a case, it is desirable that the viewing angle characteristic of the display device is narrow. However, it is desired that the display device has a function of controlling the viewing angle because there are occasions when the displayed image is observed by a plurality of people. Not limited to this, it is desired that mobile devices and public information terminal devices also have the function of controlling the viewing angle.

WO2008/114677 JP-A-6-59287

This embodiment provides a viewing angle control device and a display device capable of controlling the viewing angle.

A viewing angle control device according to one embodiment includes:
a first polarizing plate having a first easy transmission axis orthogonal to the reference axis; a second polarizing plate having a second easy transmission axis orthogonal to the reference axis and facing the first polarizing plate; and the first polarized light a first substrate positioned between a plate and the second polarizing plate; a first electrode positioned between the first substrate and the second polarizing plate; and a first orientation axis parallel to the reference axis. a first alignment film located between the first electrode and the second polarizing plate; a second substrate located between the second polarizing plate and the first alignment film; and the first alignment film; and a second alignment film having a second alignment axis parallel to the reference axis and located between the second electrode and the first alignment film. and a liquid crystal layer having a liquid crystal material containing a plurality of liquid crystal molecules and a dichroic dye containing a plurality of dichroic dye molecules and positioned between the first alignment film and the second alignment film. a viewing angle control panel ; and a control section for controlling driving of the first electrode and the second electrode, and the liquid crystal layer has a long axis of each of the liquid crystal molecules parallel to the reference axis in plan view. A first state in which the long axis forms a first tilt angle with respect to the reference axis, and a first state in which the long axis of each of the liquid crystal molecules is parallel to the reference axis in plan view, and the long axis is in parallel with the reference axis. and a second state in which a second tilt angle larger than the first tilt angle is formed with respect to the axis , and the first alignment film and the second alignment film are horizontal alignment films, respectively. , the liquid crystal layer has a positive dielectric anisotropy and adopts homogeneous alignment, and the controller controls the first electrode and the second electrode when the liquid crystal layer is switched to the first state. and a voltage in the range of 3 to 7 V is applied between the first electrode and the second electrode when the liquid crystal layer is switched to the second state.

Further, the display device according to one embodiment includes:
a first polarizing plate having a first easy transmission axis orthogonal to the reference axis; a second polarizing plate having a second easy transmission axis orthogonal to the reference axis and facing the first polarizing plate; and the first polarized light a first substrate positioned between a plate and the second polarizing plate; a first electrode positioned between the first substrate and the second polarizing plate; and a first orientation axis parallel to the reference axis. a first alignment film located between the first electrode and the second polarizing plate; a second substrate located between the second polarizing plate and the first alignment film; and the first alignment film; and a second alignment film having a second alignment axis parallel to the reference axis and located between the second electrode and the first alignment film. and a liquid crystal layer having a liquid crystal material containing a plurality of liquid crystal molecules and a dichroic dye containing a plurality of dichroic dye molecules and positioned between the first alignment film and the second alignment film. A viewing angle control panel, a display panel for displaying an image , and a control section for controlling driving of the first electrode and the second electrode, and are positioned between the viewing angle control panel and the display panel. The polarizing plate is either one of the first polarizing plate and the second polarizing plate, and the liquid crystal layer has a long axis of each of the liquid crystal molecules parallel to the reference axis in a plan view. forms a first tilt angle with respect to the reference axis, and the long axis of each of the liquid crystal molecules is parallel to the reference axis in plan view, and and a second state in which a second tilt angle is larger than the first tilt angle, wherein the first alignment film and the second alignment film are horizontal alignment films, respectively, and the liquid crystal layer is a , has a positive dielectric anisotropy and adopts a homogeneous alignment, and the control unit applies a voltage of 0 V between the first electrode and the second electrode when the liquid crystal layer is switched to the first state. A voltage in the range of 3 to 7 V is applied between the first electrode and the second electrode when a voltage is applied and the liquid crystal layer is switched to the second state.

FIG. 1 is a cross-sectional view showing the display device according to the first embodiment. 2 is a sectional view showing the display panel shown in FIG. 1. FIG. 3 is a cross-sectional view showing the viewing angle control panel, the first polarizing plate, and the second polarizing plate shown in FIG. 1. FIG. FIG. 4 is an exploded perspective view showing the second polarizing plate, the liquid crystal layer of the viewing angle control panel, and the first polarizing plate. FIG. 5 is a cross-sectional view showing part of the display panel, the first polarizing plate, and the second polarizing plate, showing a state in which no voltage is applied to the liquid crystal layer. 6 is a plan view showing the liquid crystal layer shown in FIG. 5. FIG. FIG. 7 is a cross-sectional view showing part of the display panel, the first polarizing plate, and the second polarizing plate, and shows a state in which a voltage is applied to the liquid crystal layer. 8 is a plan view showing the liquid crystal layer shown in FIG. 7. FIG. FIG. 9 is a graph showing changes in the contrast ratio with respect to the angle of inclination from the front direction of the screen of the display device when the guest content in the liquid crystal layer is 0%, 1%, 2%, and 3%. FIG. 4 is a diagram showing; FIG. 10 is a graph showing changes in contrast ratio with respect to the content when the angle is 50°. FIG. 11 is a graph showing the change in light transmittance with respect to the angle when the content is 1%, 2%, and 3%. FIG. 12 is a plot diagram showing changes in light transmittance with respect to the content in the front direction (the angle=0°). FIG. 13 is a graph showing changes in brightness with respect to the voltage applied to the liquid crystal layer when the angle is 50° in the first embodiment and the second comparative example. FIG. 14 is a graph showing changes in luminance level with respect to the angle when the voltage is 4 V in the first embodiment and the second comparative example. 15 is a cross-sectional view showing a viewing angle control panel, a first polarizing plate, and a second polarizing plate of a display device according to Modification 1 of Embodiment 1. FIG. 16 is a cross-sectional view showing a viewing angle control panel, a first polarizing plate, a second polarizing plate, a third polarizing plate, and a fourth polarizing plate of a display device according to Modification 3 of Embodiment 1. FIG. . FIG. 17 is a cross-sectional view showing the display device according to the second embodiment.

Hereinafter, each embodiment and each modification of the present invention will be described with reference to the drawings. It should be noted that the disclosure is merely an example, and those skilled in the art will naturally include within the scope of the present invention any appropriate modifications that can be easily conceived while maintaining the gist of the invention. In addition, in order to make the description clearer, the drawings may schematically show the width, thickness, shape, etc. of each part compared to the actual embodiment, but this is only an example, and the interpretation of the present invention is not intended. It is not limited. In addition, in this specification and each figure, the same reference numerals may be given to the same elements as those described above with respect to the existing figures, and detailed description thereof may be omitted as appropriate.

(First embodiment)
First, the display device DSP according to the first embodiment will be described. FIG. 1 is a cross-sectional view showing a display device DSP according to the first embodiment.
As shown in FIG. 1, the display device DSP includes a first polarizing plate PL1, a second polarizing plate PL2, a viewing angle control panel VP, a display panel PNL for displaying an image, a third polarizing plate PL3, an illumination It comprises a device BU and a control unit CON.

The second polarizing plate PL2 is arranged to face the first polarizing plate PL1. The viewing angle control panel VP is arranged between the first polarizer PL1 and the second polarizer PL2. The display panel PNL is arranged to face the viewing angle control panel VP. The polarizing plate positioned between the viewing angle control panel VP and the display panel PNL is either the first polarizing plate PL1 or the second polarizing plate PL2. In this embodiment, the polarizing plate positioned between the viewing angle control panel VP and the display panel PNL is the second polarizing plate PL2. The display panel PNL is positioned between the second polarizer PL2 and the third polarizer PL3. The first polarizing plate PL1 is positioned between the illumination device BU and the viewing angle control panel VP.

The control unit CON is electrically connected to each of the viewing angle control panel VP, the display panel PNL, and the lighting device BU, and controls driving of each of the viewing angle control panel VP, the display panel PNL, and the lighting device BU. is configured to

The illumination device BU of this embodiment is a backlight unit. The illumination device BU emits diffused light. The viewing angle control panel VP has a first state in which the light incident from the lighting device BU side together with the first polarizing plate PL1 and the second polarizing plate PL2 is emitted as diffused light, and a second state in which the light is condensed and emitted. , . Note that the above-mentioned condensed emission means condensing and emitting light in the normal direction of the surface of the second polarizing plate PL2 on the display panel PNL side.

Diffused light or light with higher directivity than the diffused light is incident on the display panel PNL. When the diffused light is incident on the display panel PNL, the display device DSP widens the viewing angle θ to display an image. On the other hand, when light with higher directivity than the diffused light enters the display panel PNL, the display device DSP narrows the viewing angle θ to display an image. Here, the direction in which the first polarizing plate PL1, the viewing angle control panel VP, and the second polarizing plate PL2 are arranged and the direction orthogonal to the reference axis RA is the front direction of the display device DSP. When the display device DSP is arranged such that the reference axis RA extends vertically, the viewing angle θ is the angle of the effective viewing field on the left and right sides of the screen. The viewing angle θ in the front direction is assumed to be 0°. In this embodiment, the viewing angle θ on the left side of the front direction is represented as positive (+θ), and the viewing angle θ on the right side of the front direction is represented as negative (−θ).

The first polarizing plate PL1, the viewing angle control panel VP, the second polarizing plate PL2, the display panel PNL, and the third polarizing plate PL3 are bonded together with an adhesive layer interposed therebetween. However, between the first polarizing plate PL1, the viewing angle control panel VP, the second polarizing plate PL2, the display panel PNL, and the third polarizing plate PL3, an adhesive layer may not be interposed, and an air layer is interposed. You may have
In the display device DSP, the first polarizing plate PL1, the second polarizing plate PL2, the viewing angle control panel VP, and the control unit CON constitute a viewing angle control device.

Next, the configuration of the display panel PNL will be described. FIG. 2 is a cross-sectional view showing the display panel PNL shown in FIG.
As shown in FIGS. 1 and 2, the display panel PNL is a transmissive liquid crystal display panel. Therefore, the display device DSP of this embodiment is a liquid crystal display device. The display panel PNL is a transmissive liquid crystal display panel, and is positioned between the second polarizing plate PL2 and the third polarizing plate PL3. The display panel PNL includes an array substrate 20, a counter substrate 30 opposed to the array substrate 20 with a gap therebetween, and a liquid crystal layer 40 held between the array substrate 20 and the counter substrate 30. .

The array substrate 20 has a transparent insulating substrate 21 . A plurality of thin film transistors 22 as switching elements, a plurality of pixel electrodes 23, an alignment film 26 and the like are provided on an insulating substrate 21 . The opposing substrate 30 has a transparent insulating substrate 31 . A color filter 50 , a counter electrode 32 , and an alignment film 33 are provided on the side of the insulating substrate 31 facing the array substrate 20 . The color filter 50 has a light shielding portion 51, a peripheral light shielding portion 52, and a plurality of colored layers 53, 54, 55 of red, green, and blue. A space between the array substrate 20 and the counter substrate 30 is held by a spacer 25 . The array substrate 20 and the counter substrate 30 are bonded to each other by a sealing material 41 provided on the periphery of both substrates. The liquid crystal layer 40 is held between the array substrate 20 and the counter substrate 30 and surrounded by a sealing material 41 .

Next, configurations of the first polarizing plate PL1, the viewing angle control panel VP, and the second polarizing plate PL2 will be described. FIG. 3 is a cross-sectional view showing the viewing angle control panel VP, first polarizing plate PL1, and second polarizing plate PL2 shown in FIG. FIG. 4 is an exploded perspective view showing the second polarizing plate PL2, the liquid crystal layer 19 of the viewing angle control panel VP, and the first polarizing plate PL1.

As shown in FIGS. 3 and 4, the first polarizing plate PL1 has a first absorption axis A1a parallel to the reference axis RA. The first polarizing plate PL1 is a linear polarizing plate. The first easy transmission axis A1b of the first polarizing plate PL1 is orthogonal to the first absorption axis A1a. The second polarizing plate PL2 has a second absorption axis A2a parallel to the reference axis RA. The second polarizer PL2 is a linear polarizer. The second easy transmission axis A2b of the second polarizing plate PL2 is orthogonal to the second absorption axis A2a. The third polarizing plate PL3 (FIG. 1) has a third easy transmission axis and a third absorption axis in a predetermined direction based on the display mode of the display panel PNL.

The viewing angle control panel VP has a first substrate 11 , a first electrode 12 , a first alignment film 13 , a second substrate 15 , a second electrode 16 , a second alignment film 17 and a liquid crystal layer 19 .
The first substrate 11 is positioned between the first polarizing plate PL1 and the second polarizing plate PL2. The first substrate 11 is formed of a transparent insulating substrate such as glass or resin. The first electrode 12 is positioned between the first substrate 11 and the second polarizing plate PL2. In this embodiment, the first electrode 12 is formed on the first substrate 11 . The first electrode 12 is made of a transparent conductive material such as ITO (indium tin oxide). Also, the first electrode 12 is formed on the first substrate 11 . The first alignment film 13 is located between the first electrode 12 and the second polarizing plate PL2. In this embodiment, the first alignment film 13 is formed on the first electrode 12 and is in contact with the liquid crystal layer 19 . The first alignment film 13 has a first alignment axis AA1 parallel to the reference axis RA.

The second substrate 15 is positioned between the second polarizing plate PL2 and the first alignment film 13 . The second substrate 15 is made of a transparent insulating substrate such as glass or resin. The second electrode 16 is positioned between the second substrate 15 and the first alignment film 13 . In this embodiment, the second electrode 16 is formed on the side of the second substrate 15 facing the first alignment film 13 . The second electrode 16 is made of a transparent conductive material such as ITO. The second alignment film 17 is positioned between the second electrode 16 and the first alignment film 13 . In this embodiment, the second alignment film 17 is provided on the side of the second electrode 16 facing the first alignment film 13 and is in contact with the liquid crystal layer 19 . The second alignment film 17 has a second alignment axis AA2 parallel to the reference axis RA.

The liquid crystal layer 19 is positioned between the first alignment film 13 and the second alignment film 17 . The liquid crystal layer 19 has a liquid crystal material containing a plurality of liquid crystal molecules M1 and a dichroic dye containing a plurality of dichroic dye molecules M2. In other words, the liquid crystal layer 19 is formed by adding a dichroic dye to a liquid crystal material. In this embodiment, the concentration of the dichroic dye in the liquid crystal layer 19 is 2%. In other words, the dichroic dye content is 2%. Also, in the present embodiment, the dichroic dye (dichroic dye) is G472. However, G472 is an example of a dichroic dye, and the dichroic dye is not limited to G472.

Liquid crystal molecules M1 have a long axis LA. The dichroic dye molecule M2 is a rod-shaped compound similar to the liquid crystal molecule M1. The liquid crystal molecules M1 are initially aligned by the alignment control force of the first alignment film 13 and the second alignment film 17 . The control unit CON is configured to control driving of the first electrode 12 and the second electrode 16, for example. When a voltage is applied between the first electrode 12 and the second electrode 16, the electric field (vertical electric field) applied to the liquid crystal layer 19 controls the alignment direction of the liquid crystal molecules M1. The dichroic dye molecules M2 are aligned in the same direction as the liquid crystal molecules M1. Therefore, the direction of the dichroic dye molecules M2 changes with the switching of the liquid crystal molecules M1. From the above, the viewing angle control panel VP is composed of a guest-host mode liquid crystal panel.

In the present embodiment, the alignment directions da of the plurality of liquid crystal molecules M1 are uniform in the state (first state) in which no voltage is applied between the first electrode 12 and the second electrode 16 . In other words, the long axes LA of the plurality of liquid crystal molecules M1 are substantially aligned in one direction in the first state.

Next, a state in which no voltage is applied to the liquid crystal layer 19 of the viewing angle control panel VP will be described. FIG. 5 is a cross-sectional view showing part of the display panel PNL, the first polarizing plate PL1, and the second polarizing plate PL2, and shows a state in which no voltage is applied to the liquid crystal layer 19. FIG. The liquid crystal layer 19 shown in FIG. 5 is switched to the first state. FIG. 6 is a plan view showing the liquid crystal layer 19 shown in FIG. In addition, in FIG. 6, the liquid crystal layer 19 is viewed from the second polarizing plate PL2 side.

As shown in FIGS. 5 and 6, the first alignment film 13 and the second alignment film 17 are horizontal alignment films, respectively. Alignment treatment is applied to each of the first alignment film 13 and the second alignment film 17 . In this embodiment, the first alignment film 13 is rubbed in the first direction d1 parallel to the first alignment axis AA1. The second alignment film 17 is rubbed in a second direction d2 parallel to the second alignment axis AA2 and opposite to the first direction d1. The liquid crystal layer 19 has positive dielectric anisotropy. Therefore, the liquid crystal layer 19 adopts homogeneous alignment in the first state.

In plan view, the long axis LA of each liquid crystal molecule M1 is parallel to the reference axis RA (FIG. 6). Further, the long axis LA of each liquid crystal molecule M1 forms a first tilt angle φ1 with respect to the reference axis RA. In the first state, the first tilt angle φ1 of the liquid crystal molecules M1 near the first alignment film 13, the first tilt angle φ1 of the liquid crystal molecules M1 near the second alignment film 17, and the first alignment film of the liquid crystal layer 19 13 and the first tilt angle φ1 of the liquid crystal molecules M1 in the intermediate layer positioned between the second alignment film 17 and the second alignment film 17 are substantially the same.
By switching the viewing angle control panel VP to the first state as described above, the display device DSP can display an image with a wider viewing angle θ.

Next, a state in which a voltage is applied to the liquid crystal layer 19 of the viewing angle control panel VP will be described. FIG. 7 is a cross-sectional view showing part of the display panel PNL, the first polarizing plate PL1, and the second polarizing plate PL2, and shows a state in which a voltage is applied to the liquid crystal layer 19. FIG. The liquid crystal layer 19 shown in FIG. 7 is switched to the second state. FIG. 8 is a plan view showing the liquid crystal layer 19 shown in FIG. In addition, in FIG. 8, the liquid crystal layer 19 is viewed from the second polarizing plate PL2 side.

As shown in FIGS. 7 and 8, in the liquid crystal layer 19 in the second state, the liquid crystal molecules M1 are subjected to the alignment regulation force of the first alignment film 13 and the second alignment film 17 and the electric field applied to the liquid crystal layer 19. is working. In plan view, the long axis LA of each liquid crystal molecule M1 is parallel to the reference axis RA (FIG. 8). Further, the long axis LA of each liquid crystal molecule M1 forms a second tilt angle φ2 larger than the first tilt angle φ1 with respect to the reference axis RA.

The liquid crystal molecules M1 in the middle layer of the liquid crystal layer 19 are less affected by the alignment regulation force than the liquid crystal molecules M1 in the vicinity of the first alignment film 13 and the liquid crystal molecules M1 in the vicinity of the second alignment film 17 . Therefore, the second tilt angle φ2 of the liquid crystal molecules M1 in the intermediate layer is the largest among the second tilt angles φ2 in the second state. From the viewpoint of narrowing the viewing angle θ, when the liquid crystal layer 19 is switched to the second state, the second tilt angle φ2 of the liquid crystal molecules M1 is preferably more than 60° and less than 90° (60° <φ2<90°). In other words, the control unit CON adjusts the voltage applied between the first electrode 12 and the second electrode 16 (the voltage applied to the liquid crystal layer 19) so that the second tilt angle φ2 does not exceed 90°. is desirable.
By switching the liquid crystal layer 19 to the second state as described above, the display device DSP can display an image with a narrow viewing angle θ.

Next, the dependence of the contrast characteristics on the viewing angle θ and the density of the guest (dichroic dye) will be described. FIG. 9 is a graph showing changes in the contrast ratio with respect to the viewing angle θ when the guest concentration in the liquid crystal layer 19 is 0%, 1%, 2%, and 3%. FIG. 10 is a graph showing changes in the contrast ratio with respect to the density of the guest when the viewing angle θ is 50°.

Here, a display device having a guest concentration of 0% in the liquid crystal layer 19 will be described as a display device of Comparative Example 1. FIG. The contrast ratio shown in FIGS. 9 and 10 refers to the luminance ratio of light emitted from the second polarizing plate PL2 when the liquid crystal layer 19 is switched between the first state and the second state. Various display devices including the display device DSP of the present embodiment and the display device of Comparative Example 1 differ only in the concentration of the guest in the liquid crystal layer 19, but are configured in the same manner except for the concentration of the guest.

As shown in FIG. 9, it can be seen that the contrast ratio is substantially 1 within the range of |θ|<20°. Therefore, even if the liquid crystal layer 19 is switched from the first state to the second state in the front direction of the screen, it is possible to suppress a decrease in the luminance level of the image.
Also, the contrast ratio can be increased roughly within the range of 40°<|θ|<70°. For example, high contrast can be obtained at |θ|=50°. Therefore, it can be seen that switching the liquid crystal layer 19 to the second state narrows the viewing angle θ.

Also, it can be seen that the contrast characteristics depend not only on the viewing angle θ but also on the density of the guest (dichroic dye). When a guest is added to the liquid crystal layer 19, the contrast ratio can be made higher than when the guest is not added to the liquid crystal layer 19. FIG. Further, the contrast ratio can be increased by increasing the amount of guest added to the liquid crystal layer 19 . For example, at |θ|=50°, the contrast ratio was substantially the same when the concentration of the guest in the liquid crystal layer 19 was 2% and 3%. Viewing angle control by birefringence interference can improve the performance by making the liquid crystal layer 19 a guest host.

As shown in FIG. 10, at |θ|=50°, the contrast ratio does not rise steadily. It can be seen that the contrast ratio reaches a peak when the guest concentration is 2%, and the contrast ratio does not increase even when the guest concentration is changed from 2% to 3%.

Next, the dependence of the light transmittance on the viewing angle θ and the density of the guest (dichroic dye) will be described. FIG. 11 is a graph showing changes in light transmittance with respect to the viewing angle θ when the guest concentration in the liquid crystal layer 19 is 1%, 2%, and 3%. FIG. 12 is a plot diagram showing changes in light transmittance with respect to guest concentration in the liquid crystal layer 19 in the front direction of the screen (θ=0°). 11 and 12, the light transmittance of the display device of Comparative Example 1 is assumed to be 1, and the light transmittance is normalized.

As shown in FIG. 11, regardless of the range of the viewing angle .theta., the more the amount of guest added to the liquid crystal layer 19, the lower the light transmittance.
As shown in FIG. 12, in the front direction (θ=0°) of the screen, the light transmittance decreases downward to the right.

Based on the descriptions of FIGS. 9 to 12 as described above, from the viewpoint of the viewing angle characteristics, the concentration of the dichroic dye in the liquid crystal layer 19 is preferably within the range of 1 to 3%. More preferably, the above concentration is in the range of 2 to 3%. More preferably, the concentration is 2%.

Next, the dependence of the brightness (light transmittance) on the voltage applied to the liquid crystal layer 19 will be described. FIG. 13 is a graph showing changes in brightness with respect to the voltage applied to the liquid crystal layer 19 when |θ| In addition, in the display device of Comparative Example 2, the viewing angle control panel VP is positioned closer to the screen side of the display device than the third polarizer PL3, and the display device is configured without the second polarizer PL2. It is different from the display device DSP in form.

As shown in FIG. 13, when |θ|=50°, the brightness of the image can be increased by setting the voltage applied to the liquid crystal layer 19 to 0 V, and a slight voltage is applied to the liquid crystal layer 19. It can be seen that the brightness of the image can be darkened by doing so. It is desirable that the voltage applied to the liquid crystal layer 19 is in the range of 3 to 7V in order to darken the brightness of the image. Therefore, the controller applies a voltage of 0 V between the first electrode 12 and the second electrode 16 when the liquid crystal layer 19 is switched to the first state, and applies a voltage of 0 V when the liquid crystal layer 19 is switched to the second state. , it is desirable to apply a voltage in the range of 3 to 7 V between the first electrode 12 and the second electrode 16 . From the viewpoint of contrast characteristics (viewing angle characteristics), when the liquid crystal layer 19 is switched to the second state, the voltage applied between the first electrode 12 and the second electrode 16 is in the range of 3.5 to 5V. is more desirable. As described above, in the present embodiment, the viewing angle θ can be varied with low voltage and high efficiency.

Next, the dependence of the luminance level (light transmittance) on the viewing angle θ will be described. FIG. 14 is a graph showing the change in luminance level with respect to the viewing angle θ when the voltage applied to the liquid crystal layer 19 is 4V in this embodiment and Comparative Example 2 above.
As shown in FIG. 14, it can be seen that the viewing angle control of the display device DSP of this embodiment is superior to the viewing angle control of the display device DSP of Comparative Example 2. FIG. Therefore, as shown in FIG. 1, the viewing angle control device and the display device DSP should preferably include the second polarizing plate PL2. In other words, the viewing angle control device and the display device DSP should not be configured without the second polarizing plate PL2.

According to the viewing angle control device and the display device DSP according to the first embodiment configured as described above, the display device DSP (viewing angle control device) sets the first absorption axis A1a and the first easy transmission axis A1b to a first polarizing plate PL1, a second polarizing plate PL2 having a second absorption axis A2a and a second easy transmission axis A2b and facing the first polarizing plate PL1, and a guest-host mode liquid crystal panel. a corner control panel VP; The viewing angle control panel VP includes a first substrate 11, a first electrode 12, a first alignment film 13 having a first alignment axis AA1, a second substrate 15, a second electrode 16, and a second alignment axis AA2. and a liquid crystal layer 19 .

The liquid crystal layer 19 has a liquid crystal material containing a plurality of liquid crystal molecules M1 and a dichroic dye containing a plurality of dichroic dye molecules M2. The liquid crystal layer 19 is switched to either the first state or the second state. The first state is a state in which the long axis LA of each liquid crystal molecule M1 is parallel to the reference axis RA in plan view, and the long axis LA forms a first tilt angle φ1 with respect to the reference axis RA. The second state is a state in which the major axis LA of each liquid crystal molecule M1 is parallel to the reference axis RA in plan view, and the major axis LA forms a second tilt angle φ2 with respect to the reference axis RA.

Therefore, the display device DSP can display an image with a wide viewing angle θ in the first state, and can display an image with a narrow viewing angle θ in the second state. The viewing angle control device can emit diffused light in the first state, and can emit condensed light in the second state.

Furthermore, the display device DSP of the present embodiment can suppress a decrease in the brightness level of the image in the front direction of the screen. Compared with the display device of Comparative Example 1, the display device DSP of the present embodiment can obtain high contrast in the left and right directions toward the screen. The display device DSP of the present embodiment is superior to the display device DSP of Comparative Example 2 in terms of viewing angle control.
From the above, it is possible to obtain a viewing angle control device and a display device DSP capable of controlling the viewing angle θ.

(Modification 1 of the first embodiment)
Next, a viewing angle control device and a display device DSP according to Modification 1 of the first embodiment will be described. FIG. 15 is a cross-sectional view showing the viewing angle control panel VP, the first polarizing plate PL1, and the second polarizing plate PL2 of the display device DSP according to Modification 1 of the first embodiment.

As shown in FIG. 15, in the display device DSP of Modification 1, one of the first alignment film 13 and the second alignment film 17 may be a vertical alignment film. In Modification 1, the first alignment film 13 is a vertical alignment film. The first alignment film 13 is rubbed in the first direction d1. Therefore, in the first state, the long axis LA of the liquid crystal molecules M1 near the first alignment film 13 is not parallel to the normal to the surface of the first alignment film 13 .

In the first state, the first tilt angle φ1 of the liquid crystal molecules M1 near the first alignment film 13 is less than 90°. Further, as in the first embodiment, the major axis LA of each liquid crystal molecule M1 is parallel to the reference axis RA in plan view. The liquid crystal layer 19 has positive dielectric anisotropy. Therefore, the liquid crystal layer 19 adopts hybrid alignment in the first state.
The viewing angle control device and the display device DSP according to Modification 1 configured as described above can also obtain the same effects as those of the first embodiment.

(Modification 2 of the first embodiment)
Next, a viewing angle control device and a display device DSP according to Modification 2 of the first embodiment will be described. Although not shown, the liquid crystal layer 19 may adopt vertical alignment in the first state. Both the first alignment film 13 and the second alignment film 17 are vertical alignment films. The first alignment film 13 is rubbed in the first direction d1, and the second alignment film 17 is rubbed in the second direction d2. The liquid crystal layer 19 has negative dielectric anisotropy.
The viewing angle control device and the display device DSP according to Modification 2 configured as described above can also obtain the same effects as those of the first embodiment.

(Modification 3 of the first embodiment)
Next, a display device DSP according to Modification 3 of the first embodiment will be described. FIG. 16 shows the viewing angle control panel VP, the first polarizing plate PL1, the second polarizing plate PL2, the third polarizing plate PL3, and the fourth polarizing plate PL4 of the display device DSP according to the modification 3 of the first embodiment. It is a cross-sectional view showing the.

As shown in FIG. 16, the display device DSP may further include a fourth polarizing plate PL4. The fourth polarizer PL4 is positioned between the second polarizer PL2 and the display panel PNL. The fourth polarizer PL4 is a linear polarizer and has a fourth absorption axis A4a parallel to the second absorption axis A2a. As in the first embodiment described above, the viewing angle control panel VP and the display panel PNL may share a single second polarizing plate PL2. The polarizing plate used together with the VP and the polarizing plate used together with the display panel PNL may be separated.
In the display device DSP according to Modification 3 configured as described above, the same effects as those of the first embodiment can be obtained.

(Second embodiment)
Next, the display device DSP according to the second embodiment will be described. FIG. 17 is a cross-sectional view showing the display device DSP according to the second embodiment.
As shown in FIG. 17, the display device DSP includes a first polarizing plate PL1, a second polarizing plate PL2, a viewing angle control panel VP, a display panel PNL for displaying an image, and a control unit CON. there is The viewing angle control panel VP may be positioned closer to the screen than the display panel PNL. A polarizing plate positioned between the viewing angle control panel VP and the display panel PNL is the first polarizing plate PL1.

Various self-luminous display panels such as an organic EL (electroluminescent) display panel and a micro LED (light-emitting diode) display panel can be applied to the display panel PNL. Alternatively, various non-self-luminous display panels such as a liquid crystal display panel can be applied to the display panel PNL. In that case, the display device DSP may further include the illumination device BU.
In the display device DSP according to the second embodiment configured as described above, the same effects as those of the first embodiment can be obtained.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.
For example, the viewing angle control panel VP may be composed of a liquid crystal panel of a mode other than the guest-host mode .
The invention described in the original claims of the present application is appended below.
[1] A first polarizing plate having a first easy transmission axis orthogonal to the reference axis;
a second polarizing plate having a second easy transmission axis orthogonal to the reference axis and facing the first polarizing plate;
a first substrate positioned between the first polarizing plate and the second polarizing plate; a first electrode positioned between the first substrate and the second polarizing plate; a first alignment film having one alignment axis and positioned between the first electrode and the second polarizing plate; a second substrate positioned between the second polarizing plate and the first alignment film; a second electrode located between the second substrate and the first alignment film; and a second alignment axis parallel to the reference axis and located between the second electrode and the first alignment film. a liquid crystal layer having a second alignment film and a liquid crystal material including a plurality of liquid crystal molecules and a dichroic dye including a plurality of dichroic dye molecules and positioned between the first alignment film and the second alignment film; and a viewing angle control panel having
The liquid crystal layer is
a first state in which the major axis of each liquid crystal molecule is parallel to the reference axis in plan view and the major axis forms a first tilt angle with respect to the reference axis;
a second state in which the long axis of each of the liquid crystal molecules is parallel to the reference axis in plan view, and the long axis forms a second tilt angle larger than the first tilt angle with respect to the reference axis;
can be switched to either
Viewing angle control device.
[2] The concentration of the dichroic dye in the liquid crystal layer is in the range of 1 to 3%.
The viewing angle control device according to [1].
[3] the first alignment film and the second alignment film are horizontal alignment films;
the liquid crystal layer has a positive dielectric anisotropy and adopts a homogeneous alignment;
The viewing angle control device according to [1].
[4] when the liquid crystal layer is switched to the second state, the second tilt angle is greater than 60° and less than 90°;
The viewing angle control device according to [3].
[5] further comprising a control unit for controlling driving of the first electrode and the second electrode;
The control unit
applying a voltage of 0 V between the first electrode and the second electrode when the liquid crystal layer is switched to the first state;
applying a voltage in the range of 3 to 7 V between the first electrode and the second electrode when the liquid crystal layer is switched to the second state;
The viewing angle control device according to [3].
[6] when the liquid crystal layer is switched to the second state, the voltage is in the range of 3.5 to 5V;
The viewing angle control device according to [5].
[7] a first polarizing plate having a first easy transmission axis orthogonal to the reference axis;
a second polarizing plate having a second easy transmission axis orthogonal to the reference axis and facing the first polarizing plate; a first substrate positioned between the first polarizing plate and the second polarizing plate; a first electrode positioned between the first substrate and the second polarizing plate; and a first electrode having a first orientation axis parallel to the reference axis and positioned between the first electrode and the second polarizing plate. a first alignment film, a second substrate positioned between the second polarizing plate and the first alignment film, a second electrode positioned between the second substrate and the first alignment film, and a second alignment film having a second alignment axis parallel to a reference axis and positioned between the second electrode and the first alignment film; a liquid crystal material including a plurality of liquid crystal molecules; and a plurality of dichroic dye molecules. a viewing angle control panel, comprising: a liquid crystal layer having a dichroic dye containing
a display panel for displaying an image;
the polarizing plate positioned between the viewing angle control panel and the display panel is either one of the first polarizing plate and the second polarizing plate;
The liquid crystal layer is
a first state in which the major axis of each liquid crystal molecule is parallel to the reference axis in plan view and the major axis forms a first tilt angle with respect to the reference axis;
a second state in which the long axis of each of the liquid crystal molecules is parallel to the reference axis in plan view, and the long axis forms a second tilt angle larger than the first tilt angle with respect to the reference axis;
can be switched to either
display device.
[8] The concentration of the dichroic dye in the liquid crystal layer is in the range of 1 to 3%.
The display device according to [7].
[9] the first alignment film and the second alignment film are horizontal alignment films;
the liquid crystal layer has a positive dielectric anisotropy and adopts a homogeneous alignment;
The display device according to [7].
[10] When the liquid crystal layer is switched to the second state, the second tilt angle is greater than 60° and less than 90°.
The display device according to [9].
[11] further comprising a control unit for controlling driving of the first electrode and the second electrode;
The control unit
applying a voltage of 0 V between the first electrode and the second electrode when the liquid crystal layer is switched to the first state;
applying a voltage in the range of 3 to 7 V between the first electrode and the second electrode when the liquid crystal layer is switched to the second state;
The display device according to [9].
[12] when the liquid crystal layer is switched to the second state, the voltage is in the range of 3.5 to 5 V;
The display device according to [11].
[13] a third polarizing plate;
further comprising a lighting device;
the polarizing plate positioned between the viewing angle control panel and the display panel is the second polarizing plate;
The display panel is a transmissive liquid crystal display panel and is positioned between the second polarizing plate and the third polarizing plate,
The first polarizing plate is positioned between the lighting device and the viewing angle control panel,
The display device according to [7].

DSP...display device, PNL...display panel, CON...control section,
PL1, PL2, PL3, PL4... Polarizing plate PL, VP... Viewing angle control panel,
DESCRIPTION OF SYMBOLS 11, 15... Substrate, 12, 16... Electrode, 13, 17... Alignment film, 19... Liquid crystal layer,
M1... liquid crystal molecule, M2... dichroic dye molecule, LA... long axis, RA... reference axis,
A1a, A2a, A4a... absorption axis, A1b, A2b... easy transmission axis,
AA1, AA2: Orientation axis, θ: Viewing angle, φ1, φ2: Tilt angle.

Claims (9)

a first polarizing plate having a first easy transmission axis orthogonal to the reference axis;
a second polarizing plate having a second easy transmission axis orthogonal to the reference axis and facing the first polarizing plate;
a first substrate positioned between the first polarizing plate and the second polarizing plate; a first electrode positioned between the first substrate and the second polarizing plate; a first alignment film having one alignment axis and positioned between the first electrode and the second polarizing plate; a second substrate positioned between the second polarizing plate and the first alignment film; a second electrode located between the second substrate and the first alignment film; and a second alignment axis parallel to the reference axis and located between the second electrode and the first alignment film. a liquid crystal layer having a second alignment film and a liquid crystal material including a plurality of liquid crystal molecules and a dichroic dye including a plurality of dichroic dye molecules and positioned between the first alignment film and the second alignment film; and a viewing angle control panel ;
A control unit that controls driving of the first electrode and the second electrode,
The liquid crystal layer is
a first state in which the major axis of each liquid crystal molecule is parallel to the reference axis in plan view and the major axis forms a first tilt angle with respect to the reference axis;
a second state in which the long axis of each of the liquid crystal molecules is parallel to the reference axis in plan view, and the long axis forms a second tilt angle larger than the first tilt angle with respect to the reference axis;
is switched to either one of
the first alignment film and the second alignment film are horizontal alignment films,
The liquid crystal layer has positive dielectric anisotropy and adopts homogeneous alignment,
The control unit
applying a voltage of 0 V between the first electrode and the second electrode when the liquid crystal layer is switched to the first state;
applying a voltage in the range of 3 to 7 V between the first electrode and the second electrode when the liquid crystal layer is switched to the second state;
Viewing angle control device. the concentration of the dichroic dye in the liquid crystal layer is in the range of 1 to 3%;
The viewing angle control device according to claim 1. the second tilt angle is greater than 60° and less than 90° when the liquid crystal layer is switched to the second state;
The viewing angle control device according to claim 1 . the voltage is in the range of 3.5 to 5 V when the liquid crystal layer is switched to the second state;
The viewing angle control device according to claim 1 . a first polarizing plate having a first easy transmission axis orthogonal to the reference axis;
a second polarizing plate having a second easy transmission axis orthogonal to the reference axis and facing the first polarizing plate;
a first substrate positioned between the first polarizing plate and the second polarizing plate; a first electrode positioned between the first substrate and the second polarizing plate; a first alignment film having one alignment axis and positioned between the first electrode and the second polarizing plate; a second substrate positioned between the second polarizing plate and the first alignment film; a second electrode located between the second substrate and the first alignment film; and a second alignment axis parallel to the reference axis and located between the second electrode and the first alignment film. a liquid crystal layer having a second alignment film and a liquid crystal material including a plurality of liquid crystal molecules and a dichroic dye including a plurality of dichroic dye molecules and positioned between the first alignment film and the second alignment film; and a viewing angle control panel;
a display panel for displaying an image ;
A control unit that controls driving of the first electrode and the second electrode,
the polarizing plate positioned between the viewing angle control panel and the display panel is either one of the first polarizing plate and the second polarizing plate;
The liquid crystal layer is
a first state in which the major axis of each liquid crystal molecule is parallel to the reference axis in plan view and the major axis forms a first tilt angle with respect to the reference axis;
a second state in which the long axis of each of the liquid crystal molecules is parallel to the reference axis in plan view, and the long axis forms a second tilt angle larger than the first tilt angle with respect to the reference axis;
is switched to either one of
the first alignment film and the second alignment film are horizontal alignment films,
The liquid crystal layer has positive dielectric anisotropy and adopts homogeneous alignment,
The control unit
applying a voltage of 0 V between the first electrode and the second electrode when the liquid crystal layer is switched to the first state;
applying a voltage in the range of 3 to 7 V between the first electrode and the second electrode when the liquid crystal layer is switched to the second state;
display device. the concentration of the dichroic dye in the liquid crystal layer is in the range of 1 to 3%;
The display device according to claim 5 . the second tilt angle is greater than 60° and less than 90° when the liquid crystal layer is switched to the second state;
The display device according to claim 5 . the voltage is in the range of 3.5 to 5 V when the liquid crystal layer is switched to the second state;
The display device according to claim 5 . a third polarizing plate;
further comprising a lighting device;
the polarizing plate positioned between the viewing angle control panel and the display panel is the second polarizing plate;
The display panel is a transmissive liquid crystal display panel and is positioned between the second polarizing plate and the third polarizing plate,
The first polarizing plate is positioned between the lighting device and the viewing angle control panel,
The display device according to claim 5 .

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